The present invention relates generally to a composition and method for increasing the amount of cetane in fuel. More specifically, it was discovered that the amount of cetane in fuel can be increased by mixing a fuel additive comprising xcex2-carotene that was prepared in an inert atmosphere.
The interest in improving fuel efficiency has become paramount as our natural resources dwindle and the cost of fuel continues to rise. Fuel efficiency can be improved by adding a fuel additive. Several existing fuel additives are known to increase fuel efficiency, for example, U.S. Pat. Nos. 4,274,835, 5,826,369, and 6,193,766 describe fuel additives that improve combustion. Despite the successes of these inventions, there still remains a need for fuel additives that improve combustion.
Embodiments of the invention described herein concern fuel additives that increase the amount of cetane in fuel and methods of use thereof. In one embodiment, for example, a method of improving the amount of cetane in a fuel comprises the step of adding a xcex2-carotene that was dissolved in an inert atmosphere to said fuel. In another embodiment, a cetane improver is made by providing xcex2-carotene that was dissolved in an inert atmosphere, providing an alkyl nitrate, and mixing the xcex2-carotene with the alkyl nitrate. In aspects of this later embodiment, the alkyl nitrate is 2-ethylhexyl nitrate or the inert atmosphere is nitrogen. Additionally, this later method of making a cetane improver can further comprise the step of mixing the xcex2-carotene with toluene prior to mixing the xcex2-carotene with the alkyl nitrate.
Compositions of the invention can include, for example, a cetane improver made by one of the methods described above or a cetane improver comprising a non-oxygenated xcex2-carotene. These cetane improver embodiments can also comprise an alkyl nitrate and/or a toluene. Additionally, in some compositions, the alkyl nitrate is 2-ethylhexyl nitrate. A preferred embodiment of the invention is a No. 2 diesel fuel comprising one of the cetane improvers described above.
In a first embodiment, a cetane improver is provided, the cetane improver including a non-oxygenated xcex2-carotene.
In an aspect of the first embodiment, the cetane improver further includes an alkyl nitrate, such as 2-ethylhexyl nitrate.
In an aspect of the first embodiment, the cetane improver further includes a diluent, such as toluene.
In an aspect of the first embodiment, the cetane improver includes about 3 g xcex2-carotene per 3785 ml of cetane improver and about 946 ml of alkyl nitrate per 3785 ml of cetane improver. The alkyl nitrate may include 2-ethylhexyl nitrate.
In a second embodiment, a diesel fuel is provided, the diesel fuel including a base fuel and a cetane improver, the cetane improver including non-oxygenated xcex2-carotene and an alkyl nitrate.
In an aspect of the second embodiment, the alkyl nitrate includes 2-ethylhexyl nitrate.
In an aspect of the second embodiment, the diesel fuel includes from about 0.00008 g to about 0.028 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.025 g to about 8.7 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the diesel fuel includes from about 0.00024 g to about 0.024 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.075 g to about 7.5 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the diesel fuel includes from about 0.0004 g to about 0.020 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.12 g to about 6.2 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the diesel fuel includes from about 0.0006 g to about 0.016 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.19 g to about 5.0 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the diesel fuel includes from about 0.0008 g to about 0.012 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.25 g to about 3.7 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the diesel fuel includes from about 0.0016 g to about 0.0095 g xcex2-carotene per 3785 ml of the diesel fuel and from about 0.5 g to about 3 g alkyl nitrate per 3785 ml of the diesel fuel.
In an aspect of the second embodiment, the base fuel includes No. 2 diesel fuel.
In a third embodiment, a diesel fuel is provided, the diesel fuel including a base fuel and a cetane improver, the cetane improver including non-oxygenated xcex2-carotene.
In an aspect of the third embodiment, the base fuel includes No. 2 diesel fuel.
In a fourth embodiment, a method of increasing a cetane number of a fuel is provided, the method including dissolving xcex2-carotene in a diluent under an inert atmosphere to yield a cetane improver; and adding the cetane improver to a base fuel to yield an additized fuel, such that the cetane number of the additized fuel is higher than the cetane number of the base fuel.
In an aspect of the fourth embodiment, the base fuel includes diesel fuel, such as No. 2 diesel fuel.
In an aspect of the fourth embodiment, the base fuel further includes toluene as a diluent.
In an aspect of the fourth embodiment, inert atmosphere includes nitrogen.
In an aspect of the fourth embodiment, the method further includes the step of mixing an alkyl nitrate with the cetane improver. The alkyl nitrate may include 2-ethylhexyl nitrate.